tools/perf/util/thread.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <errno.h>
   3 #include <stdlib.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <linux/kernel.h>
   7 #include <linux/zalloc.h>
   8 #include "dso.h"
   9 #include "session.h"
  10 #include "thread.h"
  11 #include "thread-stack.h"
  12 #include "debug.h"
  13 #include "namespaces.h"
  14 #include "comm.h"
  15 #include "map.h"
  16 #include "symbol.h"
  17 #include "unwind.h"
  18 #include "callchain.h"
  19
  20 #include <api/fs/fs.h>
  21
  22 int thread__init_maps(struct thread *thread, struct machine *machine)
  23 {
  24         pid_t pid = thread->pid_;
  25
  26         if (pid == thread->tid || pid == -1) {
  27                 thread->maps = maps__new(machine);
  28         } else {
  29                 struct thread *leader = __machine__findnew_thread(machine, pid, pid);
  30                 if (leader) {
  31                         thread->maps = maps__get(leader->maps);
  32                         thread__put(leader);
  33                 }
  34         }
  35
  36         return thread->maps ? 0 : -1;
  37 }
  38
  39 struct thread *thread__new(pid_t pid, pid_t tid)
  40 {
  41         char *comm_str;
  42         struct comm *comm;
  43         struct thread *thread = zalloc(sizeof(*thread));
  44
  45         if (thread != NULL) {
  46                 thread->pid_ = pid;
  47                 thread->tid = tid;
  48                 thread->ppid = -1;
  49                 thread->cpu = -1;
  50                 thread->lbr_stitch_enable = false;
  51                 INIT_LIST_HEAD(&thread->namespaces_list);
  52                 INIT_LIST_HEAD(&thread->comm_list);
  53                 init_rwsem(&thread->namespaces_lock);
  54                 init_rwsem(&thread->comm_lock);
  55
  56                 comm_str = malloc(32);
  57                 if (!comm_str)
  58                         goto err_thread;
  59
  60                 snprintf(comm_str, 32, ":%d", tid);
  61                 comm = comm__new(comm_str, 0, false);
  62                 free(comm_str);
  63                 if (!comm)
  64                         goto err_thread;
  65
  66                 list_add(&comm->list, &thread->comm_list);
  67                 refcount_set(&thread->refcnt, 1);
  68                 RB_CLEAR_NODE(&thread->rb_node);
  69                 /* Thread holds first ref to nsdata. */
  70                 thread->nsinfo = nsinfo__new(pid);
  71                 srccode_state_init(&thread->srccode_state);
  72         }
  73
  74         return thread;
  75
  76 err_thread:
  77         free(thread);
  78         return NULL;
  79 }
  80
  81 void thread__delete(struct thread *thread)
  82 {
  83         struct namespaces *namespaces, *tmp_namespaces;
  84         struct comm *comm, *tmp_comm;
  85
  86         BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
  87
  88         thread_stack__free(thread);
  89
  90         if (thread->maps) {
  91                 maps__put(thread->maps);
  92                 thread->maps = NULL;
  93         }
  94         down_write(&thread->namespaces_lock);
  95         list_for_each_entry_safe(namespaces, tmp_namespaces,
  96                                  &thread->namespaces_list, list) {
  97                 list_del_init(&namespaces->list);
  98                 namespaces__free(namespaces);
  99         }
 100         up_write(&thread->namespaces_lock);
 101
 102         down_write(&thread->comm_lock);
 103         list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
 104                 list_del_init(&comm->list);
 105                 comm__free(comm);
 106         }
 107         up_write(&thread->comm_lock);
 108
 109         nsinfo__zput(thread->nsinfo);
 110         srccode_state_free(&thread->srccode_state);
 111
 112         exit_rwsem(&thread->namespaces_lock);
 113         exit_rwsem(&thread->comm_lock);
 114         thread__free_stitch_list(thread);
 115         free(thread);
 116 }
 117
 118 struct thread *thread__get(struct thread *thread)
 119 {
 120         if (thread)
 121                 refcount_inc(&thread->refcnt);
 122         return thread;
 123 }
 124
 125 void thread__put(struct thread *thread)
 126 {
 127         if (thread && refcount_dec_and_test(&thread->refcnt)) {
 128                 /*
 129                  * Remove it from the dead threads list, as last reference is
 130                  * gone, if it is in a dead threads list.
 131                  *
 132                  * We may not be there anymore if say, the machine where it was
 133                  * stored was already deleted, so we already removed it from
 134                  * the dead threads and some other piece of code still keeps a
 135                  * reference.
 136                  *
 137                  * This is what 'perf sched' does and finally drops it in
 138                  * perf_sched__lat(), where it calls perf_sched__read_events(),
 139                  * that processes the events by creating a session and deleting
 140                  * it, which ends up destroying the list heads for the dead
 141                  * threads, but before it does that it removes all threads from
 142                  * it using list_del_init().
 143                  *
 144                  * So we need to check here if it is in a dead threads list and
 145                  * if so, remove it before finally deleting the thread, to avoid
 146                  * an use after free situation.
 147                  */
 148                 if (!list_empty(&thread->node))
 149                         list_del_init(&thread->node);
 150                 thread__delete(thread);
 151         }
 152 }
 153
 154 static struct namespaces *__thread__namespaces(const struct thread *thread)
 155 {
 156         if (list_empty(&thread->namespaces_list))
 157                 return NULL;
 158
 159         return list_first_entry(&thread->namespaces_list, struct namespaces, list);
 160 }
 161
 162 struct namespaces *thread__namespaces(struct thread *thread)
 163 {
 164         struct namespaces *ns;
 165
 166         down_read(&thread->namespaces_lock);
 167         ns = __thread__namespaces(thread);
 168         up_read(&thread->namespaces_lock);
 169
 170         return ns;
 171 }
 172
 173 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
 174                                     struct perf_record_namespaces *event)
 175 {
 176         struct namespaces *new, *curr = __thread__namespaces(thread);
 177
 178         new = namespaces__new(event);
 179         if (!new)
 180                 return -ENOMEM;
 181
 182         list_add(&new->list, &thread->namespaces_list);
 183
 184         if (timestamp && curr) {
 185                 /*
 186                  * setns syscall must have changed few or all the namespaces
 187                  * of this thread. Update end time for the namespaces
 188                  * previously used.
 189                  */
 190                 curr = list_next_entry(new, list);
 191                 curr->end_time = timestamp;
 192         }
 193
 194         return 0;
 195 }
 196
 197 int thread__set_namespaces(struct thread *thread, u64 timestamp,
 198                            struct perf_record_namespaces *event)
 199 {
 200         int ret;
 201
 202         down_write(&thread->namespaces_lock);
 203         ret = __thread__set_namespaces(thread, timestamp, event);
 204         up_write(&thread->namespaces_lock);
 205         return ret;
 206 }
 207
 208 struct comm *thread__comm(const struct thread *thread)
 209 {
 210         if (list_empty(&thread->comm_list))
 211                 return NULL;
 212
 213         return list_first_entry(&thread->comm_list, struct comm, list);
 214 }
 215
 216 struct comm *thread__exec_comm(const struct thread *thread)
 217 {
 218         struct comm *comm, *last = NULL, *second_last = NULL;
 219
 220         list_for_each_entry(comm, &thread->comm_list, list) {
 221                 if (comm->exec)
 222                         return comm;
 223                 second_last = last;
 224                 last = comm;
 225         }
 226
 227         /*
 228          * 'last' with no start time might be the parent's comm of a synthesized
 229          * thread (created by processing a synthesized fork event). For a main
 230          * thread, that is very probably wrong. Prefer a later comm to avoid
 231          * that case.
 232          */
 233         if (second_last && !last->start && thread->pid_ == thread->tid)
 234                 return second_last;
 235
 236         return last;
 237 }
 238
 239 static int ____thread__set_comm(struct thread *thread, const char *str,
 240                                 u64 timestamp, bool exec)
 241 {
 242         struct comm *new, *curr = thread__comm(thread);
 243
 244         /* Override the default :tid entry */
 245         if (!thread->comm_set) {
 246                 int err = comm__override(curr, str, timestamp, exec);
 247                 if (err)
 248                         return err;
 249         } else {
 250                 new = comm__new(str, timestamp, exec);
 251                 if (!new)
 252                         return -ENOMEM;
 253                 list_add(&new->list, &thread->comm_list);
 254
 255                 if (exec)
 256                         unwind__flush_access(thread->maps);
 257         }
 258
 259         thread->comm_set = true;
 260
 261         return 0;
 262 }
 263
 264 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 265                        bool exec)
 266 {
 267         int ret;
 268
 269         down_write(&thread->comm_lock);
 270         ret = ____thread__set_comm(thread, str, timestamp, exec);
 271         up_write(&thread->comm_lock);
 272         return ret;
 273 }
 274
 275 int thread__set_comm_from_proc(struct thread *thread)
 276 {
 277         char path[64];
 278         char *comm = NULL;
 279         size_t sz;
 280         int err = -1;
 281
 282         if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
 283                        thread->pid_, thread->tid) >= (int)sizeof(path)) &&
 284             procfs__read_str(path, &comm, &sz) == 0) {
 285                 comm[sz - 1] = '\0';
 286                 err = thread__set_comm(thread, comm, 0);
 287         }
 288
 289         return err;
 290 }
 291
 292 static const char *__thread__comm_str(const struct thread *thread)
 293 {
 294         const struct comm *comm = thread__comm(thread);
 295
 296         if (!comm)
 297                 return NULL;
 298
 299         return comm__str(comm);
 300 }
 301
 302 const char *thread__comm_str(struct thread *thread)
 303 {
 304         const char *str;
 305
 306         down_read(&thread->comm_lock);
 307         str = __thread__comm_str(thread);
 308         up_read(&thread->comm_lock);
 309
 310         return str;
 311 }
 312
 313 /* CHECKME: it should probably better return the max comm len from its comm list */
 314 int thread__comm_len(struct thread *thread)
 315 {
 316         if (!thread->comm_len) {
 317                 const char *comm = thread__comm_str(thread);
 318                 if (!comm)
 319                         return 0;
 320                 thread->comm_len = strlen(comm);
 321         }
 322
 323         return thread->comm_len;
 324 }
 325
 326 size_t thread__fprintf(struct thread *thread, FILE *fp)
 327 {
 328         return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
 329                maps__fprintf(thread->maps, fp);
 330 }
 331
 332 int thread__insert_map(struct thread *thread, struct map *map)
 333 {
 334         int ret;
 335
 336         ret = unwind__prepare_access(thread->maps, map, NULL);
 337         if (ret)
 338                 return ret;
 339
 340         maps__fixup_overlappings(thread->maps, map, stderr);
 341         maps__insert(thread->maps, map);
 342
 343         return 0;
 344 }
 345
 346 static int __thread__prepare_access(struct thread *thread)
 347 {
 348         bool initialized = false;
 349         int err = 0;
 350         struct maps *maps = thread->maps;
 351         struct map *map;
 352
 353         down_read(&maps->lock);
 354
 355         maps__for_each_entry(maps, map) {
 356                 err = unwind__prepare_access(thread->maps, map, &initialized);
 357                 if (err || initialized)
 358                         break;
 359         }
 360
 361         up_read(&maps->lock);
 362
 363         return err;
 364 }
 365
 366 static int thread__prepare_access(struct thread *thread)
 367 {
 368         int err = 0;
 369
 370         if (dwarf_callchain_users)
 371                 err = __thread__prepare_access(thread);
 372
 373         return err;
 374 }
 375
 376 static int thread__clone_maps(struct thread *thread, struct thread *parent, bool do_maps_clone)
 377 {
 378         /* This is new thread, we share map groups for process. */
 379         if (thread->pid_ == parent->pid_)
 380                 return thread__prepare_access(thread);
 381
 382         if (thread->maps == parent->maps) {
 383                 pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
 384                          thread->pid_, thread->tid, parent->pid_, parent->tid);
 385                 return 0;
 386         }
 387         /* But this one is new process, copy maps. */
 388         return do_maps_clone ? maps__clone(thread, parent->maps) : 0;
 389 }
 390
 391 int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone)
 392 {
 393         if (parent->comm_set) {
 394                 const char *comm = thread__comm_str(parent);
 395                 int err;
 396                 if (!comm)
 397                         return -ENOMEM;
 398                 err = thread__set_comm(thread, comm, timestamp);
 399                 if (err)
 400                         return err;
 401         }
 402
 403         thread->ppid = parent->tid;
 404         return thread__clone_maps(thread, parent, do_maps_clone);
 405 }
 406
 407 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
 408                                         struct addr_location *al)
 409 {
 410         size_t i;
 411         const u8 cpumodes[] = {
 412                 PERF_RECORD_MISC_USER,
 413                 PERF_RECORD_MISC_KERNEL,
 414                 PERF_RECORD_MISC_GUEST_USER,
 415                 PERF_RECORD_MISC_GUEST_KERNEL
 416         };
 417
 418         for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
 419                 thread__find_symbol(thread, cpumodes[i], addr, al);
 420                 if (al->map)
 421                         break;
 422         }
 423 }
 424
 425 struct thread *thread__main_thread(struct machine *machine, struct thread *thread)
 426 {
 427         if (thread->pid_ == thread->tid)
 428                 return thread__get(thread);
 429
 430         if (thread->pid_ == -1)
 431                 return NULL;
 432
 433         return machine__find_thread(machine, thread->pid_, thread->pid_);
 434 }
 435
 436 int thread__memcpy(struct thread *thread, struct machine *machine,
 437                    void *buf, u64 ip, int len, bool *is64bit)
 438 {
 439        u8 cpumode = PERF_RECORD_MISC_USER;
 440        struct addr_location al;
 441        long offset;
 442
 443        if (machine__kernel_ip(machine, ip))
 444                cpumode = PERF_RECORD_MISC_KERNEL;
 445
 446        if (!thread__find_map(thread, cpumode, ip, &al) || !al.map->dso ||
 447            al.map->dso->data.status == DSO_DATA_STATUS_ERROR ||
 448            map__load(al.map) < 0)
 449                return -1;
 450
 451        offset = al.map->map_ip(al.map, ip);
 452        if (is64bit)
 453                *is64bit = al.map->dso->is_64_bit;
 454
 455        return dso__data_read_offset(al.map->dso, machine, offset, buf, len);
 456 }
 457
 458 void thread__free_stitch_list(struct thread *thread)
 459 {
 460         struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
 461         struct stitch_list *pos, *tmp;
 462
 463         if (!lbr_stitch)
 464                 return;
 465
 466         list_for_each_entry_safe(pos, tmp, &lbr_stitch->lists, node) {
 467                 list_del_init(&pos->node);
 468                 free(pos);
 469         }
 470
 471         list_for_each_entry_safe(pos, tmp, &lbr_stitch->free_lists, node) {
 472                 list_del_init(&pos->node);
 473                 free(pos);
 474         }
 475
 476         zfree(&lbr_stitch->prev_lbr_cursor);
 477         zfree(&thread->lbr_stitch);
 478 }